[Bug] Avatar shown without permission [added 2.4]

[Kirby]

Description
The users avatar is shown in posts even if the user does not have permission

Steps to reproduce
1) Setup a User that has a usergroup that allows custom avatars and make sure that Keep Custom Avatar in user manager is set to No
2) Upload an avatar for this user
3) Make a post to an image - Avatar is being shown
4) Change usergroup permissiosn for this user so he does not have permission to use custom avatars
5) View the image again - the avatar is still being shown

Fix
Needs to check Bitfield genericpermissions & canuseavatar and use[adminavatar]

[Zachariah]

gallery/showimage.php

Find:

Content visible to verified customers only.

Replace:

Content visible to verified customers only.

Added to 2.4